In general, phenol is manufactured by oxidizing cumene to form the hydroperoxide of cumene, followed by cleavage of the cumene hydroperoxide with an inorganic acid such as sulfuric acid to form a cumene hydroperoxide cleavage product. Some processes oxidize s-butylbenzene, either alone or in combination with cumene, to produce s-butylbenzene hydroperoxide.
A cumene oxidation product generally contains dimethylbenzyl alcohol (DMBA). Where the oxidation feed comprises s-butylbenzene, the oxidation product also generally comprises ethyl methyl benzyl carbinol (EMBA). It is desirable to maximize conversion of DMBA in the oxidation product to α-methyl styrene (AMS), and to maximize conversion of EMBA in the oxidation product to α-methyl styrene (AES) and 2-phenyl-2-butene (2P2B) because these compounds can be hydrogenated to produce cumene and s-butylbenzene for recycle back to the oxidation reactors, which increases overall conversion efficiency.
Unfortunately, many cleavage reactions are run at relatively high reaction temperatures. For example, the reaction temperature in typical boiling pot reactions is from about 75° C. to about 85° C. At such high reaction temperatures, significant amounts of DMBA, EMBA, product AMS, product AES, and product 2P2B are converted to “non-recoverable by-products.”
Methods are needed which decrease the loss of DMBA and EMBA to non-recoverable by-products.